Lists are a prominent part of most graphical user interfaces and are typically used to display a list of selections available to a user. For example, clicking on a toolbar item usually causes a list to drop down or pop up from the toolbar. A user may then make a selection from the drop down list that is revealed.
In a desktop computing environment, lists commonly consist of a vertical column of text items, in which text is displayed to indicate the function of the button. The functionality provided by such a list is adequate for the needs required by most applications that run on the desktop system. In some systems, such as the WINDOWS family of operating systems produced by MICROSOFT CORP., a developer of such applications does not have to write new computer instructions, or code, for each list that the developer wants to create. Instead, a list control is provided that the developer uses to define parameters of the list. The control includes executable code that actually creates the form of the list. As a result of using such a control, the developer can become accustomed to a standard way of efficiently creating and manipulating lists.
While such a system works well for desktop environments, manufacturers of today's embedded computer products, e.g., cell phones, personal digital assistants (PDA), appliances, etc., tend to want to create a more rich visual experience to make a product more attractive to consumers. As a result, embedded computer systems are designed that provide graphical functionality that applications may use while allowing applications to control the appearance of graphics.
For example, automobile manufacturers are beginning to install one or more computers in most vehicles, the computers being used for navigation systems, sound systems, and the like. Lists are used in those systems to provide an interaction between the system and a user, e.g., a sound system may provide a list that contains several choices for CD play mode such a play, pause, repeat, etc. An automobile manufacturer wants to create a sensory experience that is unique to a particular manufacturer, so that the experience becomes associated with that manufacturer. As a part of the sensory experience, the manufacturer may want to create unique-looking lists, such as a unique way to display a CD play mode list.
The drawback in providing a unique visual experience for each different manufacturer is that applications must be created separately for each individual manufacturer. What is needed is a way to provide applications developers standardized way to create common user interface mechanisms, such as lists, while affording a product manufacturer to alter the visual appearance of the user interface.